Police excavating possible burial site of missing Northland woman Bridget Simmonds

Update: Police have discovered a body at the "site of interest".

Police are excavating a site they believe missing Northland woman Bridget Simmonds is buried.

Simmonds was reported missing on March 6, 2019, 11 days after being dropped off by her mother at the Regent Countdown in Whangārei.

On Wednesday Detective Senior Sergeant John Clayton revealed the death was being treated as suspicious after new evidence from the public.

He said they had "grave concerns" something sinister had happened to Simmonds.

Police have been carrying out search warrants on a number of rural properties in Parakao during the week and began excavating a site of interest on Friday.

They said they have reason to believe Simmonds may have been buried there.

Detective Senior Sergeant John Clayton says about 20 staff are working at the scene and the excavation process is a complex one, so it may take some time.

He says they have found some items of interest at the property and a person has been insisting in their investigation.

A scene guard will be in place overnight.